Field of the Invention
The invention concerns a multi-layer laminated preform and a method of its manufacture, as well as a method of manufacturing a container, and an accordingly manufactured container.
Multi-layer preforms as a start product for the manufacture of hollow containers such as bottles are known in various embodiments. Containers manufactured from preforms comprising several layers of differing materials will have different advantages. A combination of physical properties can be attained, for example, that cannot be achieved with a single material. Thus, materials with high heat resistance, for example, are combined with materials possessing good gas tightness or high mechanical loading capacity. Another possibility is the use of different layers of the same material, such as layers of recycled material and layers of virgin material.
The problem in the case of multi-layer containers concerns separation of wall layers, in other words delamination. For example, in the case of inhibiting the gas leakage or permeation between two layers of a container such as PET, if a gas barrier material is applied, then there will be a subsequent risk of separation of these layers during processing of the preform or storage of the container. In order to prevent such delamination, the layers can be joined together by means of an adhesive layer. Such as when copolymers containing maleic anhydride are used to adhere EVOH to polyolefins or polyesters. This requires a further layer, however, and will result in an unnecessary complication of the manufacturing process.
U.S. Pat. No. 4,980,100 discloses a multi-layer container with which delamination is prevented through the application of small perforations to the outer layer. These perforations, which approximately extend into the main delamination zone, permit the escape of gas that has collected between two layers of different gas permeability. In this way, delamination should be prevented. This method has the disadvantage that a further process step is required after completed manufacture of the container, in order to apply such apertures to the outer layer of the container.